Metering roller for fuser release oil applicator

ABSTRACT

A metering roller, for a fuser release oil applicator, which enables precise and consistent application of a predetermined target amount of release oil to the fuser roller. Starting with tubing stock that has been machined and course ground to a final outside diameter, the metering roller is produced by initial pre-finish polishing, electroplating with Nickel, heat treatment to achieve a hardened surface, and final post-finish polishing. Both pre-finish and post-finish polishing steps are performed on a lathe with continuously fed polishing paper according to a parameter recipe that includes lathe spindle rpm and lead screw speed, and polishing paper grit, feed rate, pressure, and oscillatory rate.

FIELD OF THE INVENTION

This invention relates generally to electrostatographic reproductionapparatus, and more particularly, to metering rollers in fuser releaseoil applicators.

BACKGROUND OF THE INVENTION

In typical electrostatographic reproduction apparatus, a latent imagecharge pattern is formed on a uniformly charged charge-retentive memberor photoconductor having dielectric characteristics. Chargedthermoplastic, pigmented marking particles are attracted to the latentimage charge pattern to render the latent image visible. A receivermember, such as a sheet of paper, transparency, or other medium, is thenbrought into contact with the photoconductive member, and an electricfield applied to transfer the marking particle developed image to thereceiver member from the photoconductive member. The electric field totransfer the marking particle developed image to the receiver memberfrom the photoconductive member is typically applied by spraying thebackside of the receiver member with electrically charged ions from acorona charging device, or, alternatively, by contacting the backside ofthe receiver member with an electrically biased roller. The receivermember could, alternatively, be carried on a transport member such as aflexible belt, in which case the electrically biased transfer rollercontacts the backside of the transport member that is interposed betweenthe electrically biased transfer roller and the receiver member. Anotheralternative is to first transfer the marking particle developed imagedirectly to an electrically biased intermediate transfer member in theform of a roller or belt and then from the intermediate transfer memberto the receiver member.

After transfer to the receiver member, by any of the above alternatives,the receiver member bearing the transferred marking particle image istransported to a fusing station where the marking particle image isfused to the receiver member, typically by heat and pressure, to form apermanent reproduction on the receiver member. To print an image on bothsides of the receiver member, hereafter referred to as duplex printing,a fused marking particle image is formed on side one of the receivermember by the above process, whereafter the receiver member is returnedto the process via a duplex return path wherein the receiver member isturned over so as to have a second marking particle developed imagetransferred and fused to side two of the receiver member.

The fusing station includes a fuser member, which can be a roller, belt,or any surface having a suitable shape for fixing thermoplastic markingparticles to the receiver member. The fusing step using a roller fusermember commonly includes passing the receiver member, with the markingparticle image thereon, between a pair of engaged rollers that producean area of pressure contact known as a fusing nip. In order to form thefusing nip, at least one of the rollers typically includes a compliantor conformable layer. Heat is transferred from at least one of therollers to the marking particles in the fusing nip, causing the markingparticles to partially melt and attach to the receiver member. In thecase where the fuser member is a deformable heated roller, a resilientelastomeric layer is typically bonded to the core of the roller, withthe roller having a smooth outer surface. Where the fuser member is inthe form of a belt, e.g., a flexible endless belt that passes around theheated roller, it typically has a smooth outer surface, which may alsobe hardened.

Simplex fusing stations fuse marking particles to only one side of thereceiver member at a time. In this type of station, the engaged rollerthat contacts the unfused marking particles is commonly known as thefuser roller and is a heated roller. The roller that contacts the otherside of the receiver member is known as the pressure roller and isusually unheated. Either or both rollers can have a compliant layer onor near the surface. It is common for one of these rollers to be rotatedby an external source while the other roller is rotated frictionally bythe nip engagement.

The most common type of fuser roller is internally heated, i.e., asource of heat is provided within the roller for fusing. Such a fuserroller generally has a hollow core, inside of which is located a sourceof heat, usually a lamp. Surrounding the core can be an elastomericlayer through which heat is conducted from the core to the surface, andthe elastomeric layer typically contains fillers for enhanced thermalconductivity. In order to prevent the receiver member bearing the fusedmarking particle image from sticking to the fuser roller, release oil istypically applied to the fuser roller. The release oil is typicallyapplied to the surface of the fuser roller by an oiling mechanismincluding a wick in contact with release oil in a reservoir, a meteringroller which receives release oil from the wick, a blade which controlsthe amount of release oil on the metering roller, and a donor rollerwhich transfers the release oil from the metering roller to the fuserroller.

In electrostatographic reproduction apparatus for printing high qualitycolor images, besides fusing the pigmented marking particle image torender it permanent on the receiver member, an additional function ofthe fusing step is to impart a desired level of gloss to the fusedimage. The level of gloss imparted to the image by the fuser station istypically dependent upon such parameters as the surface finish on thefuser roller, the amount of release oil on the fuser roller, and thepressure between the fuser roller and the pressure roller. In highquality color electrostatographic reproduction apparatus it is criticalthat the predetermined target amount of release oil is applied to thefuser roller with consistent high precision and uniformity. If theamount of release oil applied to the fuser roller deviates too much fromthe predetermined target amount or if it becomes too non-uniform, imagequality defects will occur in the output prints.

A primary problem associated with too much release oil on the fuserroller occurs during duplex printing runs. As described above, in duplexprinting, a fused marking particle image is formed on side one of thereceiver member, whereafter the receiver member is returned to theprocess via a duplex return path wherein the receiver member is turnedover so as to have a second marking particle developed image transferredand fused to side two of the receiver member. When the marking particleimage on side one of the receiver member is fused in the first passthrough the fuser nip, the release oil film on the fuser roller splits,and some of the release oil transfers to side one of the receivermember. During subsequent transfer of a marking particle developed imageto side two of the receiver member, if the electric field for transferis applied by an electrically biased roller as described above, some ofthe fuser release oil from side one of the receiver member, which is nowin contact with the biased roller, transfers to the surface of thebiased roller. During a long duplex printing run a relatively largeamount of fuser release oil can thereby accumulate on the biased roller.During times such as cycle-down, non-imaging skip frames, or recoveryfrom receiver jams, the biased roller is in direct contact with thephotoconductive member. During these times some of the fuser release oilaccumulated on the biased roller during duplex printing transfers to thephotoconductive member. Release oil on the photoconductive member causesseveral types of image quality defects including background and streaksdue to non-uniform transfer from the photoconductive member to thereceiver member. These release oil related problems during duplexprinting occur much sooner if oil in excess of the predetermined targetamount is being applied to the fuser roller.

As mentioned above, the amount of release oil on the fuser rolleraffects the gloss level imparted to the high quality color image duringthe fusing step. Therefore, if the amount of release oil being appliedto the fuser roller deviates from the predetermined target amount, thegloss level of the image will also vary from the target level. Thisproblem will occur during simplex and duplex printing.

SUMMARY OF THE INVENTION

In view of the above, this invention is directed to an improved meteringroller for a fuser release oil applicator. The release oil meteringroller of this invention enables precise and consistent application of apredetermined target amount of release oil to the fuser roller of anelectrostatographic reproduction apparatus fuser, thus avoiding imagequality defects that result when the amount of release oil being appliedto the fuser roller deviates from the predetermined target amount.Applicant has discovered a novel method of providing a surface finish onthe release oil metering roller of this invention, the parameters ofwhich can be varied to achieve a predetermined target release oilmetering rate from within a range of rates, and which, additionally,precisely maintains the target metering rate under varying operatingconditions.

Starting with tubing stock that has been machined and course ground to afinal outside diameter, the method of this invention includes the stepsof pre-finish polishing of the machined and course ground tubing stock,electroplating of the tubing stock with Nickel, heat treatment of theplated tubing stock to achieve a hardened surface, and a finalpost-finish polishing of the hardened Nickel surface. Both pre-finishand post-finish polishing steps are performed on a lathe withcontinuously fed polishing paper according to a parameter recipe thatincludes the lathe spindle rpm and lead screw speed, and the polishingpaper grit, feed rate, pressure, and oscillatory rate.

The invention, and its objects and advantages, will become more apparentin the detailed description of the preferred embodiment presented below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side elevational view of an exemplary prior art fusingstation including an oiling roller mechanism with a metering roller; and

FIG. 2 shows a schematic diagram of a polishing apparatus for practicingthe method of preparing the metering roller surface, according to thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

Fusing stations and fuser rollers for use therein, including meteringroll surfaces prepared according to this invention are readilyincludable in typical electrostatographic reproduction machines of manytypes, such as for example electrophotographic color printers. Sincesuch color printers are well known in the prior art, they will not bedescribed at length herein, but only to the extent necessary for a fullunderstanding of the instant invention.

The invention relates to an electrostatographic reproduction or printingmachine for forming a toner image on a receiver member and utilizing afusing station employing a deformable fuser member for thermally fusingor fixing the toner image to a receiver member, e.g., of paper. Thedeformable fuser member can be a roller, belt, or any surface having asuitable deformable shape for fixing thermoplastic toner powder to thereceiver member. The fusing station preferably includes two rollerswhich are engaged to form a fusing nip in which an elasticallydeformable fuser roller comes into direct contact with an unfused tonerimage as the receiver member is being frictionally moved through thenip. The fuser roller may be heated by an external source of heat, suchas by direct contact with one or more heating rollers. Alternatively,the fuser roller may be heated via absorbed radiation, e.g., as providedby one or more lamps, or by any other suitable external source of heat.The toner image in an unfused state may include a single-color toner orit may include a composite image of at least two single-color tonerimages, e.g., a full color composite image made for example fromsuperimposed black, cyan, magenta, and yellow single-color toner images.The unfused toner image is previously transferred, e.g.,electrostatically, to the receiver member from one or more toner imagebearing members such as primary image-forming members or intermediatetransfer members. It is well established that for high qualityelectrostatographic color imaging with dry toners, small toner particlesare necessary.

The fusing station and fuser roller of the invention are suitable forthe fusing of dry toner particles having a mean volume weighted diameterin a range of approximately between 2 mm-9 mm, and more typically, about7 mm-9 mm, but the invention is not restricted to these size ranges. Thefusing temperature to fuse such particles included in a toner image on areceiver member is typically in a range 100° C. -200° C., and moreusually, 140°-180° C., but the invention is not restricted to thesetemperature ranges.

The electrostatographic reproduction or printing apparatus may utilize aphotoconductive electrophotographic primary image-forming member or anon-photoconductive electrographic primary image-forming member.Particulate dry or liquid toners may be used.

Turning now to the figures, FIG. 1 illustrates an exemplary simplexfusing station well known in the prior art, indicated generally by thenumeral 100. The fusing station includes an externally heated,elastically deformable fuser roller 10, engaged under pressure with arelatively harder, i.e., relatively nondeformable, pressure roller 20 soas to form a fusing nip 25. The fuser roller, described in detail below,is a multilayer roller incorporating a heat storage layer. Fuser roller10 is externally heated by direct contact with one or more heatingrollers, e.g., rollers 30 and 35. (Pressure roller 20, though not heatedby any dedicated internal or external source of heat, is generallyindirectly heated to a certain extent via contact in the nip 25). Areceiver member 15 carrying an unfused toner image 16 is shown moving indirection of arrow A, towards the fusing nip 25 for passagetherethrough. Receiver member 15 is made of any suitable material, e.g.,of paper or plastic, and the receiver member can be in cut sheet form(as depicted) or be a continuous web.

Fuser roller 10 generally includes a rigid, cylindrical, core member 11,around which is a deformable annular structure 12 including at least oneelastomeric layer. The core member 11 is preferably made of a thermallyconductive material such as a metal, preferably aluminum, and the coremember is typically (but not necessarily) hollow as shown. Preferably anouter diameter of the core member is in a range between about 5 inchesand 7 inches, and the outer diameter is more preferably about 6.0inches. The deformable annular structure 12 includes an elastomeric basecushion layer closest to core member 11, a flexible heat storage layeraround the base cushion layer, and, a thin flexible outer gloss controllayer (release layer) around the heat storage layer (individual layersof structure 12 not separately shown). Preferably, the individual layersof structure 12 are successively coated on the core member 11 by usingsuitable coating techniques and post-coating curing and grindings ofeach successive layer as may be necessary. The outer release layer(gloss control layer) is preferably made of a low surface energymaterial such as for example a polyfluorocarbon, and preferably has avery smooth surface suitable for glossing the fused toner image.Preferably, the total thickness of the deformable annular structure 12is in a range of approximately 0.180 inch −0.240 inch, although a totalthickness outside of this range is not excluded.

It is important to have a contact width in nip 25 which is large so asto effect efficient transfer of heat from fuser roller 10 to the tonerimage 16. The contact width in nip 25 is preferably in a range ofapproximately between 15 mm-25 mm, and more preferably, 17 mm-19 mm.

Pressure roller 20 includes a rigid, cylindrical, core member 21 aroundwhich is an annular structure 22 including one or more layers, with thecore member 21 usually made of a metal, preferably aluminum, andtypically (but not necessarily) hollow as shown. Preferably an outerdiameter of the core member 21 is in a range between about 3 inches and4 inches, and the outer diameter is more preferably about 3.5 inches. Apreferred annular structure 22 includes a resilient base cushion layerand an outer layer around the base cushion layer (individual layers ofstructure 22 not separately shown). The base cushion layer of annularstructure 22 preferably has a thickness in a range of approximatelybetween 0.18 inch and 0.22 inch, and the thickness is more preferablyabout 0.20 inch. The base cushion layer of structure 22 can for examplebe made of a commercially available condensation-crosslinked PDMSelastomer which contains about 32-37 volume percent aluminum oxidefiller and about 2-6 volume percent iron oxide filler, sold by Emersonand Cuming (Lexington, Mass.) under the trade name EC 4952. Preferablythe base cushion layer of structure 22 is coated on the core member 21and the outer layer of structure 22 is formed as a topcoat layer on theunderlying base cushion layer, with the topcoat layer preferably made ofa fluorocarbon thermoplastic random copolymer (FLC) material such as forexample the copolymer of vinylidene fluoride, tetrafluoroethylene andhexafluoropropylene disclosed in Chen, et al. U.S. Pat. No. 6,429,249,issued Aug. 6, 2002. The topcoat layer thickness is preferably in arange of approximately between 0.001 inch-0.004 inches, and morepreferably 0.0015 inch-0.0025 inch. A suitable pressure roller 20 ispreferably similar to the pressure roller disclosed in Chen, et al. U.S.Pat. No. 6,660,351, issued Dec. 9, 2003. Due to the incorporatedfillers, the EC 4952 material usable for the base cushion layer ofstructure 22 has a relatively high nominal thermal conductivity of about0.35 BTU/hr/ft/° F. However, the thermal conductivity of the basecushion layer of structure 22 is not critical to the operation of fusingstation 100. In certain circumstances, a considerably lower thermalconductivity of the base cushion layer of structure 22 may be preferableso as not to drain too much heat from the contact zone of nip 25. Apreferred base cushion layer of pressure roller 20 is made of anelastomeric material having any suitable thermal conductivity, whichelastomeric material has a Shore A hardness greater than about 50,preferably greater than about 60. The base cushion layer may include aparticulate filler.

The external heating roller 30 is preferably a hard, thermallyconductive, roller. It is preferred that roller 30 be made of an annularaluminum member 31 with the outer surface (in contact with fuser roller10) being preferably anodized. Within the interior hollow of member 31is a source of heat, which source of heat is preferably a tubularheating lamp 32 coaxially located along the central longitudinal axis ofmember 31. Ohmic heating of filament 34 included in lamp 32 iscontrolled by a programmable power supply (not shown) so as to providevariable heating power, either continuously or intermittently. Anysuitable outer diameter of roller 30 may be used, with a preferred outerdiameter being about 1.0 inch. Heating roller 35 includes member 36 andlamp 37 which are respectively entirely similar to member 31 and lamp 32of roller 30, with a filament 39 of lamp 37 similarly controlled by aprogrammable power supply (not shown). Both rollers 30 and 35 arefrictionally driven by the fuser roller 10 and are engaged underpressure to form respective heating nips 33 and 38. The contact zone ofeach of nips 33 and 38 has a width, which is preferably in a range ofapproximately between 10 mm-12 mm, and more preferably about 11 mm.Preferably, the operating temperature of heating rollers 30 and 35 is ina range of approximately 230° C.-270° C., resulting in a surfacetemperature of the fuser roller 10 which is preferably in a range ofapproximately between 140° C.-170° C., with the required surfacetemperature in this range being dependent on the thickness of thereceiver members passing through nip 25. These surface temperatures aresuitable for well-known polyester toners, yet may require smalladjustments for different types of toners or unusual receiver membermaterials.

The surface temperatures of the heating rollers 30 and 35 and the fuserroller 10 are preferably measured by any suitable temperature sensingdevices external to the rollers (not shown), such as for examplecontacting sensors, in contact with each of the fuser roller and heatingrollers. Alternatively, non-contacting temperature sensors, e.g.,infrared sensors, can be used with any of these rollers. Preferably,each temperature-sensing device can be connected to a controller (notshown) for controlling the surface temperature of the respective roller.

A heating roller cleaning station 50 includes a cleaning web 55 forcleaning the surface of the fuser roller 10, a take-out spool 53 fromwhich web 55 is unwindable, and a take-up spool 54 upon which web 55 iswindable. The heating roller cleaning station 50 further includespressure backup rollers 51 and 52 for tensing the cleaning web 55against the respective heating rollers 30 and 35. Alternatively, asingle backup roller may be used (not illustrated) which presses againstboth the heating rollers 30 and 35. Web 50 is typically a single-use websuch that the entire cleaning web is discarded when the take-out spool53 is exhausted. The web 50 may be made of any suitable material, suchas for example a polyethyleneterephthalate (PET) woven fiber sold underthe tradename Nomex from DuPont.

Within the interior hollow of core member 11 is an auxiliary optionallyactivated source of heat, which internal source of heat is preferably atubular heating lamp 13 coaxially located along the central longitudinalaxis of core member 11, the lamp 13 including a filament 14.Intermittent or variable ohmic heating (as may be required) of filament14 is controllable by a programmable power supply (not shown). Theauxiliary optionally activated source of heat or lamp 13 can be usedintermittently so as to augment or supplant the heating provided by theexternal heating rollers 30 and 35. For example, the lamp 13 can beturned on when an electrostatographic printer is in standby mode inorder to keep the fuser roller 10 suitably warn, so that when theprinter is restarted the heating rollers 30 and 35 can rapidly restoresteady state thermal conditions for fusing. Conversely, when steadystate has been achieved after a start-up, any auxiliary heating may bereduced or shut off as may be necessary. The lamp 13 can also besuitably activated so as to avoid a fusing defect known as “droop”,which is the result of inadequate fusing caused by a thermal transientwhen cold receiver members first enter the fusing nip 25 after start-upof the printer after a stand-by or a shutdown.

Operating in conjunction with fusing roller 10 is an oiling rollermechanism 40 including a wick 46 in contact with a liquid release agent(e.g., fuser oil) 43 contained in reservoir 44. Wick 46 absorbs therelease agent 43 and transfers the release agent to a metering roller48, with the amount of release agent on the surface of roller 48controlled by blade 49. Metering roller 48 is in contact with arelease-agent-donor roller 47, which release-agent-donor roller contactsfuser roller 10 and thereby delivers to the surface of the fuser rollera continuous flow of release agent 43. A preferred donor roller issimilar to that of Chen, et al. U.S. Pat. No. 6,721,529, issued Apr. 13,2004. Approximately 1-20 milligrams of release agent 43 is needed foreach receiver member (e.g., receiver member sheet 15) passing throughnip 25. As is well known, a suitable release agent is typically asilicone oil. A preferred polymeric release agent 43 for use in fusingstation 100 is an amine-functionalized polydimethylsiloxane having apreferred viscosity of about 300 centipoise as disclosed in Chen, et al.U.S. Pat. No. 6,190,771, issued Feb. 20, 2001. A suitablerelease-agent-donor roller 47 for use in fusing station 10 includes forexample a hollow aluminum core of outer diameter about 0.875 inch, thecore coated by a cushion layer about 0.230 inch thick made of acompliant material having a low thermal conductivity such as for exampleobtainable commercially as S5100 from Emerson and Cuming (Lexington,Mass.), with a release layer about 0.0025 inch thick coated on thecushion layer (individual layers not illustrated in FIG. 1). The releaselayer can be made from an interpenetrating network composed of acrosslinked fluoroelastomer and two different silicone elastomers suchas disclosed in Davis, et al. U.S. Pat. No. 6,225,409, issued May 1,2001. More preferably, the release layer is made of a copolymer ofvinylidene fluoride, tetrafluoroethylene and hexafluoropropylene asdisclosed in Chen, et al. U.S. Pat. No. 6,429,249, issued Aug. 6, 2002.Any suitable dimensions of the core, cushion layer, and release layermay be used.

A release aid mechanism such as for example air knives 61 and 62 can beprovided to aid release of a fused receiver member after passage of thereceiver member through the fusing nip 25, with pressured air from airknife 61 generally directed towards the surface of fuser roller 10 andpressured air from air knife 62 generally directed towards the surfaceof pressure roller 20. Alternatively, any suitable release aid mechanismfor preventing the fused receiver member from wrapping on one or otherof rollers 10 and 20 may be used, including skives, blades, and soforth.

As mentioned above, typically approximately 1-20 milligrams of releaseagent 43 is needed to be delivered to the fuser roller 10 for eachreceiver member 15 passing through nip 25. The precise amount of releaseagent 43 required depends upon several factors including the materialand thickness of receiver member 15, the velocity at which receivermember moves through nip 25, the temperature of the fuser roller 10, thespecific rheological properties of the toner in unfused toner image 16,and the desired gloss level of toner image 16 after fusing. Typicallythe target amount of release agent 43 applied to fuser roller 10 must beheld to a tolerance of ±1.25 milligram per receiver member 15 in orderto maintain reliable performance of fusing station 100 and consistentimage quality of the fused toner image on receiver member 15. One of thefactors that critically affects the amount of release agent 43 appliedto fuser roller 10 by oiling roller mechanism 40 is the surface finishon metering roller 48. Applicant has discovered a method of providing asurface finish to metering roller 48, the parameters of which can bevaried to achieve, from within a range, a predetermined target amount ofrelease agent 43 per receiver member 15, and which, additionally,precisely maintains the target amount under varying operatingconditions.

Starting with the raw cylindrical stock, which is to become a meteringroller by the method of this invention, the first step is to grind theraw stock, for example in a lathe, to a predetermined outside diameter.In the preferred embodiment of this invention described herein thestarting raw stock is stainless steel, but it should be understood thatany other metal could be used as the starting raw stock. The remainingsteps in the method of the present invention include a pre-finishpolishing step performed on the stock that was ground to the finaldiameter in step one, plating the pre-finish polished stock with aharder material such as, for example, chrome or nickel, and a finalpost-finish polishing of the plated stock to create the finishedmetering roller.

Attention is now drawn to FIG. 2, which shows a schematic of an exampleof an apparatus in which both the pre-finish and post-finish polishingsteps of the method of this invention may be performed. In FIG. 2,numeral 200 designates the work piece in one of either the pre-finish orpost-finish polishing steps. The work piece is rotated, for example in alathe, in the direction indicated by arrow A, at a speed in the range500-1000 rpm. Polishing apparatus, designated collectively by numeral205, engages rotating work piece 200. The abrasive in the polishingsteps comprises Aluminum Oxide bonded to outer surface 215 of flexiblebelt 210. Flexible belt 210 is fed from supply roll 220 to take-up roll225, in the direction indicated by arrows B and C, in a path defined byrollers 230, 235, 240, and 245. The feed rate of flexible belt 210 fromsupply roll 220 to take-up roll 225 is in the range 2-4 inches perminute. The grit grade of the Aluminum Oxide abrasive on surface 215 isin the range 9-30 microns. Exemplary of a commercially availableabrasive that may be used in the method of this invention is 3M™Microfinishing Film-373L. The Aluminum Oxide abrasive on surface 215 offlexible belt 210 is engaged with rotating work piece 200 by roller 235,with a pressure in the range 10-15 psi. The complete polishing apparatus205 comprising Aluminum Oxide abrasive on surface 215 of flexible belt210, feed roll 220, rollers 230, 235, 240, 245, and take-up roll 225,axially traverses rotating work piece 200, at a steady speed in therange 25-35 inches per minute, while simultaneously oscillating axiallyat an oscillation rate in the range 70-90 cycles per second.

Following a pre-finish polishing step in the apparatus described above,work piece 200 is electroplated with Nickel to a minimum thickness 25.4microns. The work piece 200 is then heat treated by steadily increasingthe temperature of the work piece from ambient temperature to 750° F. inone hour, maintaining the temperature at 750° F. for three hours, andsteadily cooling the temperature from 750° F. to ambient temperature inone hour, thereby resulting in a surface hardness of the work piece inthe range 69÷4 Rockwell C. The plated and heat treated work piece 200 isthen subjected to a post-finish polishing step in the apparatusdescribed above and depicted in FIG. 2.

When a roller prepared by the method of the present invention, describedabove, is used as the metering roller 48 in oiling roller mechanism 40in FIG. 1, an oiling application rate to fuser roller 10 in the range1.5-6.0 milligrams per receiver member can be achieved by appropriateselection of the parameters of the method of this invention. Moreover,the target oiling rate selected will be held to a tolerance less than±1.25 milligrams per receiver member. The parameters of the method ofthis invention that control the target oiling rate include the gritgrade of the Aluminum Oxide abrasive on surface 215 of flexible belt210, the feed rate of flexible belt 210 from supply roll 220 to take-uproll 225, the pressure with which roller 235 is applied to work piece200, the steady rate at which the polishing apparatus 205 axiallytraverses work piece 200, and the rated at which the polishing apparatus205 axially oscillates.

EXAMPLE

An exemplary metering roller according to the method of this inventionwas prepared as follows:

1. 316 L Stainless Steel tubing stock was ground to an outside diameterof 30.1 mm.

2. The ground tubing stock was pre-finish polished by the methoddescribed above and depicted in FIG. 2 with the following set ofparameters:

-   -   Tubing stock rotational speed—570 rpm,    -   Aluminum Oxide abrasive grit—30 microns,    -   Flexible belt feed rate—4.0 inches/minute,    -   Pressure applies to tubing stock by roller 235—13 psi,    -   Steady axial speed of polishing apparatus—35 inches/minute,    -   Axial oscillating speed of polishing—8.3 cycles/second.

3. The pre-finished tubing stock was electroplated with Nickel to athickness of 8 microns.

4. The plated tubing stock was heat treated by steadily increasing thetemperature of the stock from ambient temperature to 750° F. in onehour, maintaining the temperature at 750° F. for three hours, andsteadily cooling the temperature from 750° F. to ambient temperature inone hour, thereby resulting in a surface hardness of the stock of 69Rockwell C.

5. The heat-treated tubing stock was post-finish polished by the methoddescribed above and depicted in FIG. 2 with the following set ofparameters:

-   -   Tubing stock rotational speed—1000 rpm,    -   Aluminum Oxide abrasive grit—30 microns,    -   Flexible belt feed rate—2.2 inches/minute,    -   Pressure applies to tubing stock by roller 235—10 psi,    -   Steady axial speed of polishing apparatus—25 inches/minute,    -   Axial oscillating speed of polishing—8.3 cycles/second.

The metering roller made as described above was tested in an apparatussimilar to fusing station 100 in FIG. 1, as the metering roller 48 inoiling roller mechanism 40. The fusing station 100 was substantiallythat used in a NexPress 2100 digital printing press. In printing runs aslong as 100,000 prints, the rate of release oil application to fuserroller 10 was 5.1 milligrams per receiver sheet, and held to a toleranceof ±1.25 milligrams per receiver sheet.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention.

1. A method of making a metering roller, from a cylindrical work pieceof a predetermined outside diameter, for delivering release fluid to acontact fusing device, comprising the steps of: a. polishing the axialsurface of the cylindrical work piece to a predetermined initial surfacefinish; b. increasing the hardness of said axial surface; and d.polishing said axial surface of the cylindrical work piece to apredetermined final surface finish.
 2. The method of claim 1, wherein instep b said axial surface is electroplated with Chrome.
 3. The method ofclaim 2, wherein said Electroless Nickel is plated to a minimumthickness of 25.4 microns.
 4. The method of claim 2, wherein thepolishing abrasive used in steps a and c is Aluminum Oxide, with a gritgrade in the range of 9-30 microns, bonded on a flexible film.
 5. Themethod of claim 4, wherein in steps a and c the work piece is rotated ata speed in the range 500-1000 rpm.
 6. The method of claim 5, whereinsaid Aluminum Oxide polishing abrasive engages the work piece via abacking roller, at a pressure in the range 9-15 psi.
 7. The method ofclaim 5, wherein said Aluminum Oxide polishing abrasive is fed from asupply roll to a take-up roll at a speed in the range 2-4 inches perminute.
 8. The method of claim 5, wherein said Aluminum Oxide polishingabrasive axially traverses the work piece at a speed in the range 25-35inches per minute, and axially oscillates at a rate in the range 7.0-9.0cycles per second.
 9. The method of claim 5, wherein said Aluminum Oxidepolishing abrasive engages the work piece via a backing roller, at apressure in the range 9-15 psi, is fed from a supply roll to a take-uproll at a speed in the range 2-4 inches per minute, axially traversesthe work piece at a speed in the range 25-35 inches per minute, andaxially oscillates at a rate in the range 7.0-9.0 cycles per second. 10.The method of claim 1, wherein in step c said axial surface iselectroplated with Nickel.
 11. The method of claim 10, wherein the workpiece is heat treated by steadily raising the temperature of the workpiece from ambient temperature to 750° F. in one hour, maintaining thetemperature at 750° F. for three hours, and steadily cooling thetemperature from 750° F. to ambient temperature in one hour.
 12. Themethod of claim 11, wherein said Nickel is plated to a minimum thickness25.4 microns.
 13. The method of claim 11, wherein the polishing abrasiveused in steps a and c is Aluminum Oxide, with a grit grade in the rangeof 9-30 microns, bonded on a flexible film.
 14. The method of claim 13,wherein in steps a and c the work piece is rotated at a speed in therange 500-1000 rpm.
 15. The method of claim 14, wherein said AluminumOxide polishing abrasive engages the work piece via a backing roller, ata pressure in the range 9-15 psi.
 16. The method of claim 14, whereinsaid Aluminum Oxide polishing abrasive is fed from a supply roll to atake-up roll at a speed in the range 2-4 inches per minute.
 17. Themethod of claim 14, wherein said Aluminum Oxide polishing abrasiveaxially traverses the work piece at a speed in the range 25-35 inchesper minute, and axially oscillates at a rate in the range 7.0-9.0 cyclesper second.
 18. The method of claim 14, wherein said Aluminum Oxidepolishing abrasive engages the work piece via a backing roller, at apressure in the range 9-15 psi, is fed from a supply roll to a take-uproll at a speed in the range 2-4 inches per minute, axially traversesthe work piece at a speed in the range 25-35 inches per minute, andaxially oscillates at a rate in the range 7.0-9.0 cycles per second. 19.A metering roller, for delivering release fluid to a contact fusingdevice, made by the method of claim
 1. 20. A device, for applyingrelease fluid, contained in a sump, to a contact fusing device,comprising: a donor roller rotatably supported to contact said fusingdevice; a metering roller made by the method of claim 1, said meteringroller rotatably supported to contact said donor roller and said releasefluid in said sump; and a metering blade contacting said metering rollerfor metering said release fluid to a predetermined thickness.